3D audio means audio that allows a listener to have an immersive feeling by reproducing not only an elevation of audio and a tone color but also reproducing a direction or a distance, and to which spatial information is added, wherein the spatial information makes the listener, who is not located in a space where an audio source occurred, have a directional perception, a distance perception, and a spatial perception.
When a channel signal, such as a 22.2 channel signal, is rendered into a 5.1 channel signal, a three-dimensional (3D) audio may be reproduced by using a two-dimensional (2D) output channel, however, when an elevation angle of an input channel is different from a standard elevation angle, if an input signal is rendered by using rendering parameters determined according to the standard elevation angle, distortion may occur in a sound image.